Question

Jana is proving that the following trigonometric identity is true: cos(−θ)⋅tanθ=sinθ Which step would be the first line of her proof? cosθ⋅tanθ=sinθ cos(−θ)⋅tan(−θ)=sinθ cos(−θ)⋅tanθ=sin(−θ) cosθ⋅tan(−θ)=sinθ

Answer 1

Answer:

Step-by-step explanation:

The given trigonometric identity is .

Jana has to recall that, the cosine function is an even function.

For that matter, .

Jana has to apply this property by substituting  for  in the given identity to obtain,

.

Note that, the sine and the tangent functions are odd functions